Development of technology has facilitated easy copying and transmission of digital media (audio, video, images, etc.) due to which digital media can be easily manipulated, distributed, and rendered (played) by devices, such as video players and computers, and is easily transmitted over computer networks. Due to digital media being pervasive and easily manipulated, illegal activities, such as digital piracy involving unauthorized distribution, duplication and modification are becoming increasingly prevalent. Consequently, techniques to protect owner's right of the digital media are in demand.
Digital watermarking provides copyright protection, authentication, and content tracking information. Digital watermarking may be used to embed copyright information into digital media to protect owner's right. For example, the copyright information may be embedded to protect the digital media from illegal copying and to identify manipulations in digital media. Watermarks are intended to be imperceptible to the end user of the digital media. A watermark is embedded using an algorithm and is perceptible to watermark-reading software only. Due to these widespread advantages, digital watermarking is utilized in a gamut of applications, such as image and audio protection, and video piracy preservation.
Digitally watermarked digital media may often undergo modifications. The modifications may be due to alterations done to the digital media or due to illegal distribution, copyright violation, etc. of the digital media. These modifications are commonly called as “attacks” and they degrade the quality of the watermark embedded in the media and render watermark's detection more difficult. Attacks are generally classified into unintentional and intentional attacks, wherein the intentional attacks are made during attempts to misuse or illegally distribute the digital media, undertaken by pirates. Intentional attacks generally have the objective to render the detection of watermark difficult. Unintentional attacks can be scaling, cropping, compressing, etc., of the digital media without any malicious intent of the doer. It is desirable that a watermark remains embedded in digital media, even if the digital media is subjected to such varied and different attacks.